New pipe break-in is one of those subjects that can cause a lot of arguments among smokers. My feeling is to use a common-sense approach to the matter.
The first issue is how to pack a pipe when it’s new. For years, many people have suggested starting at half a bowl and then gradually increasing over a dozen or so bowls until you are filling the pipe completely. The idea is that you will smoke all the way to the bottom, creating a protective cake throughout the entire chamber. In my opinion, there are two problems with this approach. Firstly, if carbon builds up all the way down, you will wind up having to run a drill bit through the shank to keep it clear of obstruction. Secondly, very few people smoke dry enough to keep a pipe lit until it’s completely empty. Therefore, since people rarely smoke that far down, there’s no need for any cake in the heel of the chamber. I recommend packing and smoking the pipe normally, while trying to smoke especially slowly during the first dozen of bowls.
The next issue is in treating the chamber with fluids like honey or saliva to accelerate the build up of cake. I strongly disagree with this approach. Using anything to expedite the development of a carbon layer generally leads to a soft crumbly cake. Then, when you ream the chamber, the carbon can come out in chunks, leaving thin or bare spots where the heat can attack the wood.
Please note that meerschaum pipes should definitely be smoked normally from the beginning, and that the chamber should be wiped out after each bowl, as a cake should not be allowed to accumulate in these pipes at all.
Also, plan on reaming your briars when they have a cake as thick as a nickel. Cut it back to the thickness of a dime. Allowing the cake to get too thick can cause the bowl to crack, as the cake will expand at a different rate than the wood.
Finally, if the pipe has a uncoated chamber that is stained (i.e.- Peterson pipes), I like to wipe out the pipe with a high-proof liquor four to five times before I ever smoke it. The stain can seal the wood, which makes it difficult for the carbon to stick. Since the stain used for pipes is usually alcohol-based, using liquor works very well to remove it, and it won’t leave a bad taste in the pipe, unlike rubbing or denatured alcohol.